A multimode wireless device supports multiple RATs (radio access technologies) and typically operates on multiple frequency bands. As a first example, a wireless device might support GSM/GPRS/EDGE (Global System for Mobile communications/General Packet Radio Service/Enhanced Data rates for GSM Evolution), UMTS/HSPA (Universal Mobile Telecommunications System/High-Speed Packet Access), and CDMA2000 1x/1xEV-DO (Code Division Multiple Access 2000 1x/1x Evolution-Data Optimized or 1x Evolution-Data only). As a second example, a wireless device might support GSM/GPRS/EDGE, and UMTS/HSPA. Other wireless devices might support a different set of RATs.
Most regulated licensed frequency bands are typically allocated to be used by multiple air interfaces (or equivalently multiple RATs) as shown in the following table.
Frequency BandAir Interfaces (RATs)(downlinkGSM/GPRS/cdma2000 1x/frequency)EDGEUMTS/HSPA1xEV-DO 869-894 MHzknown cellularknown as band Vknown as band850 MHz bandclass 0 or NAcellular band1930-1990 MHzknown as PCSknown as band IIknown as band1900 MHz bandclass 1 or PCSband 925-960 MHzknown as E-GSMknown as bandknown as bandVIII, currentlyclass 9 (notbeing deployeddeployed yet)2100-2170 MHzNoknown as band Iknown as bandclass 6 (notdeployed yet)1805-1880 MHzknown as GSMknown as band IIIknown as band1800(not deployedclass 8 (notyet)deployed yet)For example, a 60-MHz-wide PCS band and 25-MHz-wide cellular band can be split into multiple blocks and allocated to a first provider (GSM/GPRS/EDGE+UMTS/HSPA operator), a second provider (cdma2000 1x/1xEV-DO operator), and a third provider (GSM operator).
A wireless device acquires a network of a given RAT by using a transceiver that is specific to the RAT in order to receive service. As indicated in the table above, each RAT typically operates on multiple frequency bands. Therefore, there are numerous possibilities in terms of supported frequency bands and supported RATs. A wireless device might scan all of the supported frequency bands and all of the supported RATs in order to search for a network. With the introduction of more frequency bands and RATs, the amount of network scanning that a multi-mode device performs can become excessive. Excessive network scanning is undesirable because it takes time, consumes battery power, occupies communication resources, introduces latency to provide service, etc.